Couplers (or couplings) are well-known devices to interconnect hoses or tubes in a fluid flow system. A coupler typically includes a coupler socket (female element) and a nipple (male element). The coupler socket is attached by a first conduit to a source of fluid, e.g., a pressurized tank, while the nipple is attached by a second conduit to e.g., a tool, machine or dispense head. When the nipple is inserted into the coupler socket, a closure valve mounted within the socket opens to provide a fluid flow path through the coupler. At the same time, a catch or coupling mechanism automatically engages the nipple to retain the nipple within the socket. The coupling mechanism can be manually released to disconnect the nipple from the coupler socket. Such a coupler is typically referred to as a "push-to-connect" coupler.
The nipple for the coupler includes a tubular shank or plug circumscribing a central bore, and a downstream port which enables the nipple to be connected to the conduit. The shank of the nipple narrows down and includes a circumferential groove or channel toward the inlet end. When the nipple is inserted into the socket, the coupling mechanism is received in the groove and engages the shank to retain the nipple within the coupler socket.
A number of different types of coupler sockets have been developed for retaining the nipple within the coupler. One popular type of coupler socket includes a cylindrical body having an internal wall or partition extending perpendicular to the axis of the coupler which fluidly separates the inlet end of the body from the outlet end of the body. A first radial passage is formed axially along the body on one side of the wall, while a second radial passage is formed axially along the body on the other side of the wall. A sleeve surrounds the cylindrical body and includes a cylindrical channel along the inside surface. When the sleeve is in a first position (the closed position), the channel is aligned with only one of the radial passages and fluid is prevented from flowing through the coupler. When the sleeve is moved axially with respect to the coupler into a second position (the open position), the channel is aligned with both of the radial passages, and fluid can bypass the internal wall and flow through the coupler. Movement of the sleeve allows the user to pressurize or depressurize the conduit from the coupler as desired. Movement of the sleeve (or a separate sleeve surrounding the coupler body) also allows the user to disengage the coupling mechanism, such that the nipple can be removed from the coupler socket. The above-described coupler is shown for example, in U.S. Pat. Nos. 3,477,688; 3,106,378 and 3,106,379.
While the above couplers might be appropriate for certain applications, when the sleeve on the coupler is moved to the closed position and the nipple is separated from the coupler socket, a certain amount of fluid can be present in the outlet or downstream side of the coupler which can leak out of the coupler and dirty the user's hands and/or contaminate the surrounding area. Also, certain of the prior couplers, for example the coupler shown in U.S. Pat. No. 3,477,688, only provide for movement of the valve sleeve into a "fully open" or "fully closed" position where there is a maximum or minimum flow, and do not allow for the easy manual movement of the valve sleeve into intermediate positions for the controlled metering of fluid through the coupler (at least without having to actually hold the valve sleeve in the desired position).
As such, it is believed there is a demand in the industry for a push-to-connect type coupler which prevents leakage on the outlet side of the coupler when the nipple is removed from the coupler socket. It as also believed there is a demand for a simple coupler socket which provides quick connect and disconnect and prevents accidental disconnect without shutting off flow through the coupler. It is further believed there is a demand in the industry for a coupler which allows the metering of fluid through the coupler across a range of rates between the "fully open" and "fully closed" positions. It is still further believed that there is a continual demand in the industry for a push-to-connect type coupler which is reliable and which is easy to manufacture, assemble and use.